Cathode-ray tube with target support



Dec. 20, 1955 FAULKNER ETAL 2,728,009

CATHODE-RAY TUBE WITH'TARGET SUPPORT Filed Nov. 14, 1950 Z //Vl/ N70 Bic/24nd D. mil/mi fir 0e EBar/zes; and M520 J Grimes ATTORNEY United States Patent CATHODE-RAY TUBE WITH TARGET SUPPORT Richard D. Faulkner and Bryce E. Barnes, Lancaster, and Milton J. Grimes, Ephrata, Pa., assignors to Radio Corporation of America, a corporation of Delaware Application November 14, 1950, Serial No. 195,588

16 Claims. (Cl. 313-89) This invention relates to improvements in cathode-ray tubes and to improvements in the art of manufacturing the same.

The principal object of the invention is to provide a tube structure which shall lend itself readily for use in the manufacture of color kinescopes and other beam tubes of the kind where optimum performance can be achieved only when the gun elements and the target or screen elements are mounted in substantially perfect alignment.

Another object of the invention is to provide a metal tube-envelope having a main chamber capable of accommodating a thin-metal target or other easily distortable electrode structure, and of a construction calculated to protect said electrode structure from warping due to the high temperatures normally employed in forming a hermetic seal between the separable metal parts of the envelope.

Another and specific object of the invention is to provide an improved method of and apparatus for aligning an electron gun, or a battery of guns, with respect to a screenassembly of the masked-target variety.

Stated generally, the foregoing and other objects are achieved, in accordance with the invention, by the provision of a metal envelope having a face plate or window which is open during the assembly and alignment of the electrode elements of the device, and by the provision on the inner wall of the envelope of mounting brackets or lugs which serve, during the electrode assembly-operation, to support a jig for aligning the gun structure of the device with respect to the plane ultimately occupied by the target or screen assembly. The face plate of the tube comprises the base of a bowl-shape closure member, within which the screen assembly is received. The closure member is provided with an outwardly extending flange which, when placed in juxtaposition with a complementary flange on the outer surface of the envelope, may be welded in place without risk of overheating any part of the screen assembly. Whenever it is necessary or expedient to provide a metal shell within the envelope, for the purpose of protecting the beam fiom the disturbing effects of stray magnetic fields, the metal shell or shield may conveniently be supported upon the same mounting lugs that support the target or screen assembly.

The invention is described in greater detail in connection with the accompanying single sheet of drawings, wherein:

Fig. 1 is an exploded view, partly in section, of a cathode ray tube embodying the invention,

Fig. 2 is a fragmentary sectional View of one corner of the main chamber of the tube of Fig. 1, subsequent to its assembly, and showing the manner in which the target or screen assembly and the window or face plate of the tube are mounted.

Fig. 3 is a view similar to Fig. 2, showing an altemative form of mounting lug support for supporting the target or screen,

Fig. 4 is a rear elevation of a jig employed during the assembly operation for aligning the neck and the gun 2,728,0fi9 Patented Dec. 2 0, 1955 ice structure of the tube with respect to the plane of the target or screen, and,

Fig. 5 is a broken sectional view of the neck of the tube with the centering portion or mandrel of the jig positioned therein during the assembly operation. v

As shown in the exploded view (Fig. l) the envelope of the cathode-ray tube of the invention consists, essentially, of four discrete parts, 1 to 4 inclusive. The main chamber 5 (Fig. 2) of the envelope comprises (a) the hollow metal frustum 3 of a cone, pyramid or similar body and (b) the bowl-shape closure member 4 for the large open end or base of the frustum. The other two parts of the envelope comprise an elongated cylindrical glass neck 2 which can be hermetically sealed to the edge of the narrow end of the frustum 3, and a glass closure element or stem 1 for the free open-end of the neck. As will hereinafter more fully appear, the stem 1 also serves as a support for an electron gun 6, the barrel of which is accommodated Within the neck 2.

The base of the bowl-shape closure element 4 is constituted of glass and comprises the face plate or Window 7 of the tube. The sides of the bowl 4 comprise a metal window-frame 8 which, when joined to the frustum 3, defines a part of the main chamber 5 of the tube. The large open end of the frustum 3 terminates in an outwardly extending peripheral flange 9. The metal window frame 8 terminates at its inner or open end in a similar outwardly extending peripheral flange 10 which, when placed in juxtaposition with the first flange 9, can be hermetically sealed thereto as by a weld 11 (Fig. 2).

In accordance with the invention, the main chamber 5 of the envelope is provided with three or more mounting brackets or lugs 12 which are disposed in equally spaced circumferential array 0n the inner surface 3a of the frustum adjacent to its large open-end or base. These lugs 12 are preferably constituted of metal and may be welded to the inner surface 3a of the frustum, with or without the use of rivets 14 (Fig. 2).

The lug 12 shown in Fig. 2 comprises a straight arm a and an integral angularly extending arm b. The inner arm a preferably has an outer surface a of the same curvature or contour as that of the surface 3a to which it is affixed. The angular arm b extends into the bowl or closure member 4 along a line parallel to the central axis xx of the envelope. A somewhat more economical use of the space within the front closure 4 of the envelope can be achieved when the lugs are of the wedge-shape contour shown at 12' in Fig. 3. Here it will be observed that the slanting face b of the wedge extends parallel to the inclined surface of the metal frustum 3. Thus, the presence of the lugs 12' does not limit the useful area of the window 7, or of the screen-area scanned by the beam from the gun 6 (Fig. 1). In both cases, however, the lugs 12 (Fig. 2) or 12' (Fig. 3) extend forwardly well beyond the plane of the flange 9 on the rim of the frustum and terminate in locating surfaces (13, Fig. 2; 13', Fig. 3) lying in a common plane P (Fig. 2, P, Fig. 3) normal to the tube axis x-x, Fig. 1, in the space normally defined by the window 7 and frame 8 of the bowl-shaped closure 4. The free end of each lug contains a threaded hole for receiving a complementarily threaded mounting screw 15.

When it is necessary or expedient to shield the main chamber of the tube against stray-magnetic fields the lugs 12 may be employed as combined spacers and supports for the shield 16. When the lugs 12' are of the wedgeshape contour shown in Fig. 3, the part of each lug that lies adjacent to the slanting face 3a of the envelope may be made just thick enough to establish a desired spacing between the envelope and the shell-like shield 16. In this case, the outer end of the shell is simply fitted over the adjaceht end of the lugs 12 and secured to the inclined surface 1; thereof.

Referring to Fig. 2: In the interest of rigidity, the lugs 12 may be made of a thicknessdimensiongreater than the desired ehvelope-t'o-shell spacing. In ca s e the shielding shell 16 may be supportedbymeins of 't gues f6r e'achlug) struck-'fjiit froinjthee geof the srin "513a fixed to the exposed siiffaheof the adjacent lug 12 by means of a rivety17, or by welding preyiously mentioned, the 12 inate on plane P and are each pro "ded nil/1th} threaded receiying the shank of a'sc 15; Ihe lugs ws 15 serve two function '(i) as a support for 25 "or a removabl 51 1; is 'iisd Jinf the t and assembly or the several af s'pr th are; ey serve, when thejig reino eidith rcn ig the 'stiin'i,'as 'a perm n support for the embly I8, 19,1(1 er describedl the basejzspr the 'jig within the the frustu 3 and seciii'ed near its 'lar'ger'end to theglugs 1'2, and near its other end to as table metal seat or tin-pat 20,(Fig l), provided for the urpose, on the inner are t (1" a M 31 an s 'z's ha n g hol es l h, were; each of the screws li ut it's circumference and a hen countersunk hole27 in which one end 'destal 'poi tion. 2s (Fig.5 of the jig is nefdhy the desired seeing of e lestroll-gun 6 :Eig. beam-source, respectto'the refereiie bias-e .P (Fig. 2,) of are halving green 19 its mas glfi .Th s

if 'h l ishis l i s fli 1 shewii in Fig. 5, the time; time: th li ea e so is p pvfdes w th, a. c r al 'bi fl bfe s 3 l t r. 31 h isdiine 'rie d 't'o fit snugly within the end of the her ielhf theelectrongun fijwhenthe stem'or closure ele; l) is placedon'theend of thedglassneclg 2.

, tfi rih i l q Y th..' ilaten- .f'b' e t a p fl is in t absam ehs' elements o'r diaphragms 33 (Fig. 1) Within "iIhe entir 3r """t'imea er'siera aaa ja' sgei i filrfsar imhifija and constructed with a fine degree When the seal that joins thels't ern :1 to the of the fiieck' er th'etubl'e has hardened, the screws that hold I v e of the ji'g to thelugs 11 arerfemovedandthe eh re g i s withdrawtn'throughthe still een front er d of the 'co'ne'o'r tantrum-3; The "same screws 15tlfat held the base 25 of the jig to the lugs 12 may then beernplbyd in securing the screen'or target assembly 1819 (Fig. 2) tofsaid lugs.

When the screen toward which the electrons are rooted is of the fmasked target variety, the correct ng betwe'en the apertured thin-metal mask "18 iand alignment of its apertures with respect to the phosphor crne its 12p of its viewing screen 19 '(Fig. 2 inay be di y a suitable frame or other spacing element 40 during the manufacture of this sub-assembly, for example,

v 5 a 1." i ia e e g tic 'shielid or shell 16 1s entered Into 1n Figsa 5 the Basset the comprises a, hyph ns, The lengthof met ZS isderod ZS is provided, adjacent tqiits free the target assembly to the several lugs 12. As shown in Fig. 3, when the tube'employsa single screen or target element 19', said'elernent may be secured directly as the lugs 12.

When the screen or target assembly has been secured to the brackets or lugs 12 the bowl-shape closure element 4 is placed over the open end of the frustum 3. The outwardly extending peripheral flanges 9 and 10 on said tube parts are then placed in juxtaposition, where they may beheld by a suitable clamp (not shown), during the forrnation of the weld 11 at the outer extremities of "said flanges.

Ihe weld 11 is preferably, but not necessarilybmade is n. ner s ou atm phc e heat pp during the welding operation is dissipated, to a substantial dcgree in the flanges 9 and 10 (which maybe said to arson? a hmtafin fi n) n in th a i thin e e t ts f th rn slop l d d wframe 8- one practical embodimentof the invention the glass window 1 was found to be fully protect ed frorn the heat of the weld when 'the envelope 3 and window-frame '8 were made of geropeor an inch thick and the axial length of the windowframe was about two inches.v Any heat that may be tr'ansferred by conduction through the metal envelope is barredbythe length and mass of the lugs. 12, from reaching the easily warped thin metal mask 18 and the temperature sensitive phosphor elements 19p of the s??? a e bl a from the foregoing itiwill be apparent that the present invention provides an improvedjcathodeqay tube structure and one which may bie used fo r color kinescopes M other precisi on-bi ilt tnhes, including those com I g thin-metal or other easily distortable temperature sensitive electrod elements.

ha is ai d i a cathode-ray tube comprising an envelope having centralaxis and an inner surface surrounding said axis defining a boundary of the main chamber of said tube, a plurality'of brackets mounted in circumfeifentially spaced array on said innersurface of said enyelopeand terminating within said chamber in a comn on plane normal to said axis, and means for securing a t arget electrode to said brackets adjacentto said'commoi! IRl r-Wv we v I 2. Ih einvention as set forth in claim 1 and wherein said inner snrface of said envelope is inclined with respectto said axis and said jbrackets extendalong said i sur s? 9 a v ope- The nv mi n a s t forth axis in a directionfsubstantially parallel to said inclined in claim 1 and wherein said inner surface of said envelope is inclined with re secured to said lugs, said lugs extending .beyondsaid open-end of said shell and terminating in a commomplan'c vithin said enyelope, and means fonsecuring 'a ta'i get electrode toJ-said lugs in said common plane,

'6. A cathode-ray tube assembly comprising "an envelope having an open end terminating in an outwardly extending peripheral flange, a pluralityof lugsrhounted in spaced array on the inner surface of said envelope adjacent to said open end, said lugsextending outwardly beyond said open end of said envelope and terminating in a common plane remote from said flange, means for securing a target electrode to said lugs in said common plane, and a closure element for said open-end of said envelope, said closure element comprising a window having a vacuum-tight window frame of a diameter sufliciently large to receive said target electrode and terminating at its rim in an outwardly extending metal flange disposed in juxtaposition with respect to said first men tioned flange and hermetically sealed thereto.

7. A cathode-ray tube comprising an envelope including a wall in the form of a frustrum having a smaller and a larger end and intervening between a neck portion and an end portion of the tube, a plurality of brackets mounted in circumferentially spaced array on the inner surface of said wall adjacent to its larger end and a target assembly mounted on said brackets and comprising a plate having a ray-sensitive coating thereon and a foraminous electrode mounted adjacent to said coated plate on the side facing the neck portion of the tube.

8. A cathode-ray tube comprising an envelope including a wall in the form of a frustrum having a smaller and a larger end and intervening between a neck portion and an end portion of the tube, a plurality of brackets mounted in circumferentially spaced array on said wall adjacent to its larger end, a target assembly mounted on said brackets and comprising a plate having a ray-sensitive coating thereon and an apertured electrode mounted adjan cent to the ray-sensitive coated plate on the side facing the neck portion of the tube, and a metallic shield extending along the inner surface of said wall and mounted at one of its ends on said brackets.

9. A cathode-ray tube comprising an envelope having a substantially frustro-conical wall intervening between a neck portion and an end portion of the tube, a plurality of brackets secured to the wall adjacent to its larger end, a target assembly mounted on said brackets and comprising a plate having a ray-sensitive coating thereon and an apertured electrode mounted adjacent to the phosphor coated plate on the side facing the neck portion of the tube, a metallic shield extending along the inner surface of said wall having tongues cut therefrom to provide slots interfitting with the brackets and means for securing the tongues to the brackets to secure the shield to the wall.

10. A'cathode-ray tube comprising an envelope having a neck portion, an end portion, and an intervening portion, the intervening portion having a smaller end toward the neck portion and a larger end toward the end portion of the tube, a plurality of brackets mounted in circumferentially spaced array on the larger end of the intervening portion, and a target assembly mounted on said brackets and comprising a plate having a phosphor coating thereon and a foraminous electrode mounted adjacent to the phosphor coated plate on the side facing the neck portion of the tube.

11. A cathode-ray tube comprising an envelope having a neck portion, an end portion, and an intervening portion having a smaller end toward the neck portion and a larger end toward the end portion of the tube, a plurality of brackets mounted adjacent to the larger end of the intervening portion, a target mounted on said brackets, and a metallic shield extending along the inner surface of said intervening portion and mounted at one of its ends on said brackets, the inner surfaces of the brackets extending between the shield and the target substantially in line with the surface of the shield.

12. A cathode-ray tube comprising an envelope having a neck-portion adapted to accommodate a source of electrons, a bowl-like end-portion adapted to accommodate a target for electrons from said source, and an intermediate hollow portion through the interior of which electrons pass in their transit from said source to said tar- 6 get; said intermediate portion having a small end toward said neck-portion and a larger end toward said bowl-like portion, said bowl-like end-portion and said larger end of said intermediate-portion having complementary circumferentially extending flange means hermetically sealed about the periphery thereof, and means supported by said flange-means for supporting a target electrode in a position to be scanned by electrons from said source.

13. A cathode-ray tube comprising an envelope having a neck-portion adapted to accommodate a source of electrons, a bowl-like end-portion adapted to accommodate a target including at least one element to be scanned by electrons from said source, and an intermediate hollow portion through the interior of which electrons normally pass in their transit from said source to said target, said intermediate portion having a small end toward said neckportion and a larger end toward said bowl-like portion, said bowl-like end-portion and said larger end of said intermediate-portion having outwardly extending circumferentially disposed flanges arranged thereon in juxtaposition and hermetically sealed together adjacent to their outer extremities, and means supported in contact with the flange on said intermediate portion of said envelope for supporting said target-element in a position to be scanned by electrons from said source.

14. A cathode-ray tube including an envelope having a neck-portion for receiving a source of electrons, a bowllike end-portion for accommodating a target element toward which electrons from said source are directed, and an intermediate envelope portion through which electrons pass to said target element, said intermediate portion increasing in transverse section from said neck-portion to said end-portion, the larger end of said intermediate portion and said bowLlike portion having flange means the outer peripheries of which are in registry and sealed together, and lug-like supports mounted on the flange means of said intermediate envelope-portion and supporting said target element transversely of said envelope in the path of said electrons.

15. A cathode ray tube comprising an envelope having a neck-portion adapted to accommodate a beam-source of electrons, a bowl-like end-portion adapted to accommodate a target including an electrode to be scanned by beam-electrons from said source, and an intermediate hollow envelope-portion through the interior of which said beam-electrons pass in their transit to said target electrode, said intermediate envelope-portion increasing in its transverse dimensions from said neck-portion to said bowl-like end-portion, the larger end of said intermediate portion and the adjacent end of said bowl-like portion terminating in hermetically sealed metal flanges, and a plurality of metal supporting elements secured in spacedapart relationship to the metal flange of said intermediate envelope-portion and terminating in a common plane for supporting said target electrode in a position to be scanned by said beam-electrons.

16. A cathode-ray tube comprising an envelope having a central axis and an inner surface surrounding said axis and defining a boundary of the main chamber of said tube, a target electrode having an apertured central portion and a peripheral supporting portion, and means for supporting said target electrode in a predetermined position in said envelope comprising at least three supporting elements mounted in circumferentially-spaced array on said inner surface of said envelope and having locating surfaces lying substantially in a common plane normal to said axis, said peripheral supporting portion of said target electrode including a surface abutting each of the locating surfaces of said supporting elements, and means for maintaining said surfaces in said abutting relation.

References Cited in the file of this patent UNITED STATES PATENTS 1,934,821 Rudenberg Nov. 14, 1933 (Other references on following page) 

